Santro engine gets off while clutch is pressed on CNG

Dear All...
my santro engine gets shutdown while applying breaks and shifting to low rpm while pressing clutch. it happen only in cng, not on petrol. Before that it was giving problem of jerks, missing on CNG till speed 20, low RPM. Now when i start the car give race, its fine... but as i try to put car in 1st gear by pressing clutch, the engine gets off, no matter how much race i am giving...

I myself own and use Santro on daily bases. As i had purchased it as used, it was not in good shape so I had faced this one and few other problems which are related. But as got used to this car, got worked on it by different mechanics trying different stuff, things are much better now. One single thing won't solve this problem, you would have to go through a checklist which include following.

1. Very first thing, get your CNG kit serviced and get any oil removed from cylinder or kit.

2. In engine compartment the box in which air filter is fixed/installed, make sure it closes properly and is not broken in anyway. Also its properly closed via clips not using small screws. Some mechanics install these screws which clip break or something so check that.

3. Their is rubber pipe with that air filter box, make sure its also closed in all ends and there is no way for extra air to in. Specially on right side a rectangle type opening on it, it must have a plastic going in from here, should not be open for air. Also make sure this pipe is not torn at any place.

4. Inside the above mentioned pipe, where it connects to air filter box, normally their is round ring inside, to narrow the pipe, to slow decrease the air going inside, check if its still in there, and no mechanic have removed it.

5. If problem still remains get you car sensors checked and get them reset.

6. I also noticed on some CNG stations' gas your car runs better than others, find one and stick to it.

These are just input from me based on personal experience, someone could add stuff and correct me if anything is off.